[Federal Register Volume 61, Number 161 (Monday, August 19, 1996)]
[Rules and Regulations]
[Pages 42776-42777]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-20873]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-177-AD; Amendment 39-9717; AD 96-17-08]
RIN 2120-AA64
Airworthiness Directives; McDonnell Douglas Model DC-10-10, -15,
-30, -40, and KC-10A (Military) Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment adopts a new airworthiness directive (AD),
applicable to certain McDonnell Douglas Model DC-10-10, -15, -30, -40,
and KC-10A (military) series airplanes, that requires modification of
the AC generator control units. This amendment is prompted by reports
of loss of electrical power from two generators and an engine that
flamed out due to an overfrequency condition of a generator. The
actions specified by this AD are intended to prevent an overfrequency
condition of a generator, which could lead to the loss of all
electrical power of the airplane.
DATES: Effective September 23, 1996.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of September 23, 1996.
ADDRESSES: The service information referenced in this AD may be
obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard,
Long Beach, California 90846, Attention: Technical Publications
Business Administration, Department C1-L51 (2-60). This information may
be examined at the Federal Aviation Administration (FAA), Transport
Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton,
Washington; or at the FAA, Los Angeles Aircraft Certification Office,
Transport Airplane Directorate, 3960 Paramount Boulevard, Lakewood,
California; or at the Office of the Federal Register, 800 North Capitol
Street, NW., suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Natalie Phan-Tran, Aerospace Engineer,
Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft
Certification Office, 3960 Paramount Boulevard, Lakewood, California
90712; telephone (310) 627-5343; fax (310) 627-5210.
SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) to include an airworthiness
directive (AD) that is applicable to certain McDonnell Douglas Model
DC-10-10, -15, -30, -40, and KC-10A (military) series airplanes was
published in the Federal Register on January 3, 1996 (61 FR 134). That
action proposed to require modification of the AC generator control
units.
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received.
Support for the Proposal
Three commenters support the proposed rule.
Request Not to Adopt the Rule
One commenter requests that the proposed AD not be adopted as
proposed. The commenter states that the modification (i.e., addition of
a circuit that will provide overfrequency protection) proposed by the
AD causes a significant reduction in the reliability of the generator
control unit (GCU). The commenter notes that, following accomplishment
of the proposed modification, it has experienced an increase of GCU
removals and bus tie relay (BTR) lockouts on in-service airplanes. The
commenter acknowledges that the subject modification may add a margin
of operating safety to the electrical generator system of Model DC-10
series airplanes; however, the commenter notes that the margin may be
eliminated with the reduction in the reliability of the GCU and
increased BTR lockouts. Therefore, the commenter concludes that the FAA
should investigate the root cause of the failure of the constant speed
drive (CSD).
The FAA does not concur with the commenters request that the
proposal not be adopted. The FAA acknowledges that the subject
modification may cause a reduction in the reliability of the GCU, which
may lead to increased removals of the GCU; and may cause an increase in
the BTR lockouts. However, the FAA has determined that the GCU's have a
low failure rate, since the overfrequency protection circuit contains a
minimum of parts; therefore, the reduction in the reliability of the
GCU will be minimal. In addition, the FAA recognizes that the BTR
lockouts may be a nuisance; however, the FAA finds that such lockouts
will not adversely affect the safety of the fleet. Furthermore, the FAA
has evaluated the root cause of the CSD failure and concluded that
there are no assurances that could prevent the failure of the CSD.
Therefore, the FAA finds that modification of the GCU's is necessary to
provide overfrequency protection as a result of failure of the CSD. An
overfrequency condition of a generator, if not corrected, could lead to
the loss of all electrical power of the airplane.
Conclusion
After careful review of the available data, including the comments
noted above, the FAA has determined that air safety and the public
interest require the adoption of the rule as proposed.
Cost Impact
There are approximately 419 Model DC-10-10, -15, -30, -40, and KC-
10A (military) series of the affected design in the worldwide fleet.
The FAA estimates that 276 airplanes of U.S. registry will be affected
by this AD, that it will take approximately 5 work hours per airplane
to accomplish the required actions, and that the average labor rate is
$60 per work hour. Required parts will cost approximately $2,896 per
generator control unit; there are 4 units per airplane. Based on these
figures, the cost impact of the AD on U.S. operators is estimated to be
$3,279,984, or $11,884 per airplane.
The cost impact figure discussed above is based on assumptions that
no operator has yet accomplished any of the requirements of this AD
action, and that no operator would accomplish those actions in the
future if this AD were not adopted.
Regulatory Impact
The regulations adopted herein will not have substantial direct
effects on the States, on the relationship between the national
government and the States, or on the distribution of power and
responsibilities among the various levels of government. Therefore, in
accordance with Executive Order 12612, it is determined that this final
rule does
[[Page 42777]]
not have sufficient federalism implications to warrant the preparation
of a Federalism Assessment.
For the reasons discussed above, I certify that this action (1) is
not a ``significant regulatory action'' under Executive Order 12866;
(2) is not a ``significant rule'' under DOT Regulatory Policies and
Procedures (44 FR 11034, February 26, 1979); and (3) will not have a
significant economic impact, positive or negative, on a substantial
number of small entities under the criteria of the Regulatory
Flexibility Act. A final evaluation has been prepared for this action
and it is contained in the Rules Docket. A copy of it may be obtained
from the Rules Docket at the location provided under the caption
ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the
Administrator, the Federal Aviation Administration amends part 39 of
the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
96-17-08 McDonnell Douglas: Amendment 39-9717. Docket 95-NM-177-AD.
Applicability: Model DC-10-10, -15, -30, -40, and KC-10A
(military) series airplanes, as listed in McDonnell Douglas Service
Bulletin DC10-24-111 RO1, Revision 1, dated August 14, 1995;
certificated in any category.
-Note 1: This AD applies to each airplane identified in the
preceding applicability provision, regardless of whether it has been
otherwise modified, altered, or repaired in the area subject to the
requirements of this AD. For airplanes that have been modified,
altered, or repaired so that the performance of the requirements of
this AD is affected, the owner/operator must request approval for an
alternative method of compliance in accordance with paragraph (b) of
this AD. The request should include an assessment of the effect of
the modification, alteration, or repair on the unsafe condition
addressed by this AD; and, if the unsafe condition has not been
eliminated, the request should include specific proposed actions to
address it.
Compliance: Required as indicated, unless accomplished
previously.
To prevent an overfrequency condition of the generator, which
could result in loss of all electrical power of the airplane,
accomplish the following:
(a) Within 2 years after the effective date of this AD, modify
the AC generator control units (GCU) in accordance with McDonnell
Douglas Service Bulletin DC10-24-111 RO1, Revision 1, dated August
14, 1995.
(b) An alternative method of compliance or adjustment of the
compliance time that provides an acceptable level of safety may be
used if approved by the Manager, Los Angeles Aircraft Certification
Office (ACO), FAA, Transport Airplane Directorate. Operators shall
submit their requests through an appropriate FAA Principal
Maintenance Inspector, who may add comments and then send it to the
Manager, Los Angeles ACO.
Note 2: Information concerning the existence of approved
alternative methods of compliance with this AD, if any, may be
obtained from the Los Angeles ACO.
(c) Special flight permits may be issued in accordance with
sections 21.197 and 21.199 of the Federal Aviation Regulations (14
CFR 21.197 and 21.199) to operate the airplane to a location where
the requirements of this AD can be accomplished.
(d) The modification shall be done in accordance with McDonnell
Douglas Service Bulletin DC10-24-111 RO1, Revision 1, dated August
14, 1995. This incorporation by reference was approved by the
Director of the Federal Register in accordance with 5 U.S.C. 552(a)
and 1 CFR part 51. Copies may be obtained from McDonnell Douglas
Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846,
Attention: Technical Publications Business Administration,
Department C1-L51 (2-60). Copies may be inspected at the FAA,
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,
Washington; or at the FAA, Los Angeles Aircraft Certification
Office, Transport Airplane Directorate, 3960 Paramount Boulevard,
Lakewood, California; or at the Office of the Federal Register, 800
North Capitol Street, NW., suite 700, Washington, DC.
(e) This amendment becomes effective on September 23, 1996.
Issued in Renton, Washington, on August 9, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service. -
[FR Doc. 96-20873 Filed 8-16-96; 8:45 am]
BILLING CODE 4910-13-P
